Former schoolteacher and longtime northwest Bronx resident Mary Mullen died on Monday morning when a fire confined to her third floor apartment on Valentine Avenue ended her life. She was 82 years old.

“It’s the end of an era,” said Maria Shkreli, owner of the building. “She has been here for about 30 years and whenever I look at old pictures of the building I think of her and the neighborhood around that time.”

A spokesman for the fire department said they were still investigating the cause of the fire that broke out around 2 a.m. in Mullen’s apartment at 2445 Valentine Ave., on the corner of 192nd Street. It took about half an hour for 60 firefighters to end the blaze and no one else was injured, the spokesman said.

From the outside, the white brick building does not reveal any fire damage, but once inside the burnt smell is pungent and unmistakable.

According to the building manager of 20 years, Maria Pimentel, Mullen kept to herself and was very religious. “Mary had a stroke and nobody knew or would have know if it wasn’t for the mail piling up and the fact she had the stroke at the diner [Louie’s Dale on 231st Street] where she used to eat,” said Pimentel, who added that Mullen was a devout catholic who regularly attended St. Philip Neri Church on the Grand Concourse.

Shkreli and Pimentel both said that Mullen was still an active person even after her stroke. With the help of her walker, she used to be out the door at 8 a.m. most days and never broke from her routine. “She would go to church, then go to the farmers market to buy her fresh fruits and eat at her favorite diner and then she would come home,” Pimentel said.

Shkreli said Mullen, who taught at PS 5 in Port Morris, was quite the character. “She was very elegant and fashionable, Shkreli said. “She always wore minks and glasses, [along] with jewelry.”

When building management moved Mullen from one apartment to another because of some hoarding tendencies, Pimentel said, Mullen decided to throw most of the stuff out.

Mary Mullen has no known immediate family, or relatives, Shkreli and Pimentel said.